Jira comment: link a PR from bitbucket

[Jeremy Fiel]

I want to link a bitbucket PR in an associated JIRA Issue comment. 

I found bitbucket can link other PR's in PR comments, but I haven't found any information for JIRA comments, specifically. 

I want similar behavior to the PR comment linking:

```

#123

<repo>/#123

<proj>/<repo>/#123

```

Intellisense look ahead functionality to display a list of matches when typing the sequence would be fantastic.